Endowment mis-selling victim John Summers was this week celebrating a £2,300 compensation payout - after originally being told he wouldn't be getting a penny. Mr Summers, 43, is disabled after losing part of a leg in a motorcycle accident and lives on benefits of £79 a week.

His experience would appear to prove what many people already suspected - that firms are rejecting mis-selling complaints but, when challenged, are then backing down and paying up.

Mr Summers is far from an isolated case, according to some. In June, Jobs & Money told how firms that mis-sold mortgage endowment policies were adding insult to injury by employing questionable tactics to cut the amount of compensation they pay. But Nationwide building society, the company involved in this latest case, denies that charge.

It is even possible (see below) to challenge the biggest roadblock on compensation - the almost automatic rejection because a policy was taken out before formal regulation began in 1988.

Mr Summers, who lives near Stroud in Gloucestershire, took out his endowment in 1987 when he bought his first house. It is an Eagle Star policy but he took it out through the Nationwide.

Four years ago he was warned there was a high risk that he would be left with a shortfall when it matures in 2012.

A little over a year ago, he went to Endowment Justice, one of a growing number of firms that go into battle on behalf of policyholders in return for a cut of any compensation (in this case, 17.5%).

The firm complained to Nationwide in October 2003 and, six months later, on April 30 this year, the society wrote back saying it was rejecting Mr Summers' claim because he had taken too long to put in his complaint.

After Endowment Justice kicked up a fuss and threatened to take the case to the Financial Ombudsman Service, Nationwide wrote back to say that "in view of the latest instruction on this matter that took effect from June 1, however, we are now prepared to...uphold the complaint".

In September, Nationwide offered Mr Summers £2,379 compensation, which he accepted, and the cheque arrived on Monday - a year and a week after the complaint was originally lodged.

"It's better than a kick in the head. I didn't expect to get anything," he told Jobs & Money.

Despite all that's happened, and the fact that the policy doesn't look likely to hit its target of £27,500, Mr Summers is going to continue paying into it every month.

He says he doesn't have any choice. He hasn't got the luxury of being able to switch to a repayment loan because he receives financial help from the government towards his mortgage payments, but this only covers the interest part of his loan.

Nationwide has a different take on the case. A spokeswoman says that in June this year, City watchdog, the Financial Services Authority, changed the rules on time limits for policyholders to complain about mis-selling (known as "time-barring").

As a result, Nationwide looked again at a number of previously excluded cases, including that of Mr Summers. He would have got his money anyway, but now will have to hand over a chunk of it to En dowment Justice, says the spokeswoman. "In the original letter we were abiding by the FSA rules... now we don't use any time-barring."

Speaking generally, Marianne Fitzjohn at Endowment Justice says she has come across lots of cases where firms reject people's com plaints but then, when they refuse to give up, eventually write back offering compensation. "We are talking about big, reputable firms who know what the rules are but are quite happy to use spurious reasons for rejecting their clients," she claims.

She also has a case on the go involving HSBC, where the compensation was calculated at "nil" - but, when the bank was asked to provide the calculations, these showed a clear financial loss of more than £3,000. Again, after the ombudsman was invoked, the bank wrote back and made an offer of compensation.

Her advice to endowment policyholders fighting for compensation is: don't give up. If the firm tries to time-bar you, or says the calculations show that you are due nothing, "don't just accept their word for it. Ask to see the evidence".